This invention relates to fluid handling devices, particularly for medical purposes, and methods of making fluid handling devices. The invention is particularly suitable for needlefree access devices and check valves.
The use of hypodermic needles to inject or withdraw fluids in medical application had been standard practice up until a few years ago. Even where a patient already had an IV tubing set connected to a vein, hypodermic needles were frequently used to inject fluids into the IV tubing. Often a “Y” access device with a septum was provided in the tubing set for this very purpose. The needle was used to puncture the septum to administer the drug or other fluid, and the septum then sufficiently sealed the opening to prevent leakage, and prevent airborne bacteria from entering the system. Septums are also common on drug vials, where the needle is inserted to withdraw a quantity of the drug.
The widespread use of hypodermic needles lead to numerous needle-stick accidents. These were not only painful, but if the needle is contaminated, could cause serious disease or complications in the needle-stick victim. There has been a desire for needlefree medical systems, where a fluid can be injected or aspirated without the use of a needle, but while maintaining an aseptic leak-free system.
Numerous devices have been developed to achieve this goal. Many of those devices have been disclosed in the patent literature. One early such device is disclosed in U.S. Pat. No. 5,360,413. The different embodiments of the needleless access device disclosed in the '413 patent have proven to be influential in the design of subsequent needlefree access devices. Many of the concepts have been used in other devices. The wiper seal to seal the inlet channel against airborne bacteria and the piston head that can be easily swabbed prior to actuation are two of the more significant features.
Even with all the work and development that has transpired over the years in this area, there is still need for improvement, particularly with respect to better performance, such as greater flow rate and reduced trapped drug and fluid after flushing, and lower cost. The preferred embodiments disclosed in the '413 patent are assembled from four or five components, depending on the design. Even though the parts can be mass produced, the product cost is dependent on the number of individual components that have to be made, and then assembled. Most needlefree access devices commonly available contain at least three parts. Many prior needlefree access devices also have internal configurations that allow fluid to be trapped in the device even after flushing. Also, many prior devices are fairly large and therefore have a higher material cost and internal volume.
Check valves are also often assembled from three or more parts. For example, U.S. Pat. Nos. 5,771,935 and 4,749,003 both disclose check valves that are assembled from three separate components. The cost of such products could be reduced if they were assembled from only two parts.
The desire to reduce the number of parts that must be assembled, however, cannot override the more important fact that the fluid handling products must meet several critical design features. Thus, there is a real need for fluid handling products that can be made at a lower cost, but still meet the end user's specifications. Also, there is a need for fluid handling products that have reduced hold up-volumes, are easier to prime and flush, and that have a flow path through the device that is visible to the user so that any bubbles can be spotted and the flow of solutions can be visualized.